| semantics). In doing so, I've come across an oddity. It seems | that Haskell does not have the principal type property It looks to me that you are correct. I hadn't realised that consequence of the dreaded M.R. It may be "well known in the Haskell community", it wasn't well known to me. John's solution is only a solution if (as he said) the call-by-need form of binding is *completely* monomorphic (not even parametric polymorphism). But then it does solve the problem, at some linguistic cost admittedly. Death to the MR! Simon